CVE-2025-21696Medium· 5.5▾ SunlitIn the Linux kernel, the following vulnerability has been resolved: mm: clear uffd-wp PTE/PMD state on mremap() When mremap()ing a memory region previously registered with userfaultfd as write-protected but without UFFD_FEATURE_EVENT_R…
▾ Sunlit zone — Low / medium · no exploitation signal
impact 30.3 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the CISA ADP record, not NVD.
Exploit-prediction probability, daily snapshots since Oct 21.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
Last analysed / modified upstream
0.2%
0.2% → 0.3%
In the Linux kernel, the following vulnerability has been resolved:
mm: clear uffd-wp PTE/PMD state on mremap()
When mremap()ing a memory region previously registered with userfaultfd as write-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in flag clearing leads to a mismatch between the vma flags (which have uffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp cleared). This mismatch causes a subsequent mprotect(PROT_WRITE) to trigger a warning in page_table_check_pte_flags() due to setting the pte to writable while uffd-wp is still set.
Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any such mremap() so that the values are consistent with the existing clearing of VM_UFFD_WP. Be careful to clear the logical flag regardless of its physical form; a PTE bit, a swap PTE bit, or a PTE marker. Cover PTE, huge PMD and hugetlb paths.
Linux >= 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 < 8e2f6ba256dd1e590addc48e6e9577bf39c482f2Linux >= 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 < 310ac886d68de661c3a334198d8604b722d7fdf8Linux >= 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 < 0cef0bb836e3cfe00f08f9606c72abd72fe78ca3Linux 5.7Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
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